Cloud storage is a mode of network online data storage; that is, the data are stored in multiple virtual servers usually managed by a third party rather than in a dedicated server. Data center operators prepare to store virtualization resources in the back-end and provide them in the way of a storage pool based on customers' demand, and then customers can use the storage pool to store files or objects by themselves. Cloud computing is an internet-based computing mode. Through this mode, the shared software and hardware resources and messages can be provided to computers and other devices as required. Cloud computing describes a new internet-based information technology (IT) service increase, use and delivery model, and usually is involved in providing dynamic, easy to expand functions and often virtualized resources via the internet. Users can access the service software and data, and service providers maintain the infrastructure and the platform to keep the service operating normally. The service software provided by service providers is often called “on-demand software”, and is usually charged based on use hours. Users only need to have software and hardware equipment with low complexity to use the service, such that enterprise costs can be saved. Because application programs are supplied centrally, updates can be published instantly without manually updating or installing new software by the user. Thus, cloud computing allows enterprises to more rapidly deploy application programs, reduce the complexity of management and maintain the cost, and allows the rapid reallocating of IT resources to cope with the fast change of enterprise requirements.
One benefit of cloud the concept is that there is no need to purchase various types of hardware equipment and software with powerful processing performance. The maintenance of the hardware equipment and the update of the software are carried out by the service provider, while the user or enterprise tries to “virtualize” the hardware equipment and software. In a communication network, application program virtualization allows the application program at the user terminal to be provided by the service terminal. However, it takes time to download an application program with larger capacity from the service terminal to the user terminal, and the application program can only be installed or executed after the download is finished. This mode of installation after download is suitable for a slow or high latency network environment. Because the bandwidth speed and retardance of a local area network and a wide area network differ greatly, in a mixed environment, this mode does not meet the needs of using an application program soon after choosing it very well.
Please refer to FIG. 1, which shows a schematic diagram of a conventional process for downloading an application program. In step S101, the user terminal system receives the instruction to start the application program. In step S102, the user terminal system determines whether a program file or cache exists, and allows the process to jump to step S103 when the program file or cache exists. In step S103, the operating system in the user terminal starts the application program. In step S102, allow the process to jump to step S104 when the program file or cache does not exist. In step S104, the server transmits all of the files of the application program to the user terminal system in their entirely, and then allow the process to jump to step S105. In step S105, the user terminal system writes the program file into the file system or the cache system, and then allows the process to go back to step S103. After step S103, the process enters Step S106. In step S106, the application program reads the program file. In order to read the program file, step S107 is used. In step S107, the application program will give an instruction to the operating system, and cause the operating system to request the file required by the application program from the file system at the user terminal. Then the file system reads the file from the hard disk and transmits it back to the operating system. In step S108, the operating system transmits it back to the application program. In step S109, execute the application program. Then repeat steps S106-S108 when it is necessary to continue executing the application program.
Please refer to FIG. 2, which shows a schematic diagram of a conventional process for executing an application program. The embodiments of steps S103, S106, S107, S108 and S109 in FIG. 1 can be illustrated by FIG. 2. Please refer to FIG. 1 and FIG. 2 simultaneously. In step S201, the user in the user terminal system starts the application program. In Step S202, the operating system at the user terminal system prepares to load the application program. In step S203, the operating system at the user terminal system receives the instructions for the application program to enable the file system to read the file blocks from the storage device. In step S204, the file system in the user terminal system reads the program file in the file blocks. In Step S205, the operating system at the user terminal system loads the program file into the memory. In Step S206, the application program takes over the operating system at the user terminal system to execute the program file, and allows the process to enter step S207 when the application program needs to execute a different process. In step S207, the operating system receives the instructions for the application program to enable the file system to read the file blocks from the storage device, and then allows the process to jump to Step S208. In step S208, the file system reads the program file in the file blocks, and then allows the process to jump to Step S206. In step S206, allow the process to jump to Step S209 to end the application program when the application program does not continue to execute other processes.
Between the service terminal and the user terminal, all the conventional modes of using the application program requires the installation or execution of the application program only after all of the files are downloaded. These modes consume substantial download time when the application program has a large capacity. For the user terminal, it is necessary to wait, which waste time. Thus, it is desirable to have a mode that allows the user terminal to use an application program soon after choosing it without requiring very much download time, and the construction of the hardware equipment with the high computing power as well as the provision and maintenance of program are provided by the service terminal.